Tantalum and/or niobium halide supported catalysts are known to be useful in various organic reactions. The compositions of these catalysts are more fully described in U.S. Pat. No. 4,480,049 and U.S. Pat. No. 4,489,171. These catalysts are not prepared utilizing the usual techniques of impregnation, but instead are prepared utilizing a method of preparation called "reactive sublimation". It is therefore useful to have a device which can be used to prepare catalysts in this manner. A device for preparing catalysts by reactive sublimation has been designed wherein tantalum and/or niobium pentahalide is sublimed and the vapor therefrom is reacted with a suitable support to produce a supported tantalum and/or niobium halide catalyst.